Regenerator



R. BECKER REGENERATOR Nov. 11, 1969 2 Sheets-Sheet 1 Filed April 9, 1968 Rudolf Becker INVENTOR.

Attorney Nov. 11, 1969 R. BECKER 3,477,496

REGENERATOR Filed April 9, 1968 2 Sheets-Sheet 2 Rudolf Becker INVENTOR.

Attorney United States Patent 56, 67 Int. Cl. F28d 17/00; F28f 27/00 US. Cl. 16510 10 Claims ABSTRACT OF THE DISCLOSURE A regenerative-type thermal-storage heat exchanger having a mass of thermal storage material formed by a plurality of radially spaced coaxial coils of solid-crosssection wire surrounding a core with the turns of each coil spaced apart by radially extending linear pieces of wire and the corresponding turns of the coils being spaced apart by axially extending, radially spaced pieces of wire, the spacer wires and the coil wires being welded together, the axial spacing between turns of each coil ranging from one fifth to one tenth the diameter of the coil wire and the spacer wires having a corresponding fraction of the diameter of the core wire, the radial spacing between coils ranging from /5 to 1 diameter of the coil wire.

My present invention relates to a regenerator and, more particularly, to a regenerative-type thermal-storage heat exchanger containing a filler constituting a thermal-storage mass adapted to retain heat or cold for subsequent heat transfer to a fluid.

In a regenerator, especially for use in Linde-Friinkl air-rectification installations and many other low-temperature processes, it is a common practice to effect an indirect heat exchange between fluids via a so-called regenerator containing a thermal-storage mass which may be cooled or heated by a first fluid passed through the mass and is used subsequently to cool or heat a second fluid. It has already been proposed to constitute the thermal-storage mass or filler of Wire, especially wire mesh or wire fabric. These regenerators have, however, the disadvantage that the mass of the fabric is relatively small and, therefore, has relatively small heat capacity so that the interaction between the thermal-storage mass and the fluid is effective only for short periods and cycling must occur at a high, often prohibitive rate, with considerable switchover losses. Other prior-art regenerators have made use of flat strips and the like, but have been characterized by excessive free volume, and low heat-transfer efficiency.

It is, therefore, the principal object of the present invention to provide an improved regenerator structure, especially for low temperature applications, which has a high ratio of heat-storage mass to volume, whose construction is relatively inexpensive, and which sustains heat exchange at a relatively high rate.

Another object of this invention is to provide a heatstorage mass for regenerative-type heat exchangers which avoids the disadvantages hitherto encountered in earlier regenerator structures.

I have now found that all of the aforementioned disadvantages may be overcome and a low-cost regenerator constructed with manufacturing simplicity, when the heatstorage mass consists of a plurality of generally helical coils of a circular cross-section wire, the helical coils being coaxial with one another but spaced apart with uniform all-around clearance. In accordance with the present invention, the helical coils are separated from one another by a first spacer means constituted of intervening arrays of axially extending, mutually parallel, but pcripherally spaced straight wires, while the turns of the coils are separated from one another by angularly spaced generally radially extending straight wires; preferably, the radially extending wires form axially spaced fanlike arrays which may be secured to a central cylindrical core about which the helical coils are built upon. A heatstorage mass of this construction has been found to be effective for many, if not all, known regenerator functions.

According to an essential feature of the present invention, the first spacer means maintains a distance between the turns of the coils in a direction perpendicular to the axis of the mass which ranges between one-fifth the diameter of the coil wire and the full diameter thereof, i.e. azllZd to 1d, where a is the radial spacing between each of the helicoidal coils and the next outermost coil and d is the diameter of the solid cross-section coil wire.

Another essential feature of this invention resides in dimensioning the pitch of the coils so that the successive turns of each coil have a spacing c ranging between one fifth and one-tenth the diameter of the coil wire (i.e. czllld to 02:1). The diameter d of the coil wire ranges between 0.5 mm. and 5.0 mm. When the coil wire (and/ or the spacer wire) are composed of ferrous metal, such as steel, it is desirable to apply a corrosion-resistant or anticorrosion coating thereon; this coating may be composed of galvanically deposited zinc. Alternatively, the wires may be composed of a material having inherently good corrosion resistance, e.g. aluminum Wire. In general, however, it is desirable to use coil wire whose diameter lies at the lower end of this range, thereby increasing the heat-transfer coeflicient and the effective surface area-to-mass ratio of the filler. However, the cost of the wire increases with decreasing wire diameter so that the price per kilogram must be weighed against the desirability of the smaller diameter wire in practical applications of the present invention.

I have found that the regenerator described above is especially desirable for use as a cold-storage receptacle in a gas-separation plant in which separation is carried out by liquefaction. In this case, the fluids passed through the mass generally comprise the relatively warm gas mixture to be rectified and cooled, and the cool separated gas fractions which may be warmed while cooling the gas. When the dimensions of the separators are within the limits given above, the filler has suflicient free space for traversal by the gas that the diameter of the regenerator can be made much smaller than earlier systems without exceeding the maximum pressure drop permissible for economical operation. Because of the ratio of filler mass to free space, switchover between cooling and heating steps can be carried out after long operating periods, thereby further decreasing switchover losses.

According to a further feature of this invention, the diameter of the coil wire may differ from one part of the regenerator to the next this construction is particularly desirable when the regenerator is employed for air rectification in which cooling of the incoming gas first involves condensation of moisture and thereafter condensation of the air. In this case, the mass extends from a relatively warm side at which the gas mixture enters to a cool side at which air condensation occurs. At the warm side, therefore, I provide coil wire of relatively large diameter so that the mass-to-surface ratio is relatively high, especially in those areas in which condensation of moisture occurs. At the cool side of the heat exchanger, the diameter of the coil wire can be reduced in a smaller interturn spacing employed so that a highly eflicient heat exchange occurs in the region in which gas liquefaction is carried out.

According to still another feature of this invention, the helical coils are wound about a cylindrical core and at least 200 coil wires are employed in coaxial configuration. The coil wires may be bounded to the spacer wires by a cementing or a welding process (e.g. by soldering or are or resistance fusion). Furthermore, the helical coils may have the same pitch so that corresponding turns of the coils lie in respective, transverse planes.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a fragmentary axial cross-sectional view of the filler for a cold-storage regenerat-or in accordance with the present invention;

FIG. 2 is a plan view thereof;

FIG. 3 is an elevational view of a portion of the mass, partially broken away;

FIG. 4 is a detail view of the junction between consecutive turns of one of the helicoidal coils; and

FIG. 5 is a plan view, corresponding to FIG. 4, showing the junction between a pair of corresponding turns of two helicoidal coils.

In the drawing, I show a heat-storage mass which comprises a x plurality of coaxial helical coils 1 through 7 of corresponding pitch and composed of a coil wire b which, as shown in FIG. 4, has an anticorrosion coating 8 of zinc or the like upon a steel core 9. The coils 1 through 7 form a coil body f surrounding a core e comprising a pair of disks 10 and 11 welded to a cylindrical sheet metal sleeve 12 which is coaxially surrounded by the coil assembly 1 and serves as a support therefor. The heat exchanger may comprise a housing represented by the dot-dash lines 13 whose heads 14 and 15 supply the fluid to, or remove the fluid from, the interior of the heat exchanger, as previously indicated. Axially extending spacer wires g define radial spacings a between the coils 1 through 7 and are disposed in angularly spaced relationship in cylindrical arrays 15 through 22, the latter arrays being disposed between the innermost coil 1 and the surface of the shell 12. 24 wires g may be provided in each array 16 through 22. The spacing a is defined by the relationship E02d to 1d, and the diameters of the wires g are generally equal to the spac ing a (FIG.

The spacers between the generally planar arrays of corresponding turns of the coils are designated as h and constitute radially extending wires whose diameter 0 is equal to substantially the spacing between the turns of the coils 1 through 7, the distance 0 being defined by the relationship CEOJd to 0.2d. Twelve such wires h are employed in each radial array thereof.

As can be seen from FIG. 4, each of the wires h contacts the succeeding turns of each coil at contact zones W and W at which the wires h are bonded to the wires b by welds. FIG. 5 shows a spacer wire g between turns of a path of adjacent coils 1 and 2 with welds w and w' as the points at which the wire b contacts the wire g.

The invention described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the appended claims.

I claim:

1. In a regenerator-type heat exchanger comprising a thermal-storage mass, the improvement wherein said thermal-storage mass includes a multiplicity of coaxial radially spaced helical wire coils each having a multiplicity of turns, first spacer means for radially separating corresponding turns of said coils by a distance a equal substantially to 0.2d to 1d where d is the diameter of the coil wire, and second spacer means separating the turns of said coils from one another by a distance 0 equal substantially to 0.1d to 0.2d.

2. The improvement defined in claim 1 wherein the coil wire has a diameter d ranging substantially from 0.5 to 5.0 mm.

3. The improvement defined in claim 1, further comprising a cylindrical core, said coils coaxially surrounding said core.

4. The improvement defined in claim 3 wherein said coils each are wound with substantially identical pitch.

5. The improvement defined in claim 1, further comprising an anticorrosion coating covering each of said coil wires.

6. The improvement defined in claim 1 wherein said first spacer means comprising a plurality of coaxial arrays of axially extending linear angularly spaced wires having a diameter substantially equal to the spacing a.

7. The improvement defined in claim 6 wherein said second spacer means includes a plurality of axially spaced arrays of linear radially extending wires each having a diameter substantially equal to the spacing c.

8. The improvement defined in claim 7 wherein the wires of said first and second spacer means and of said coils are bonded together in regions of mutual contact.

9. The improvement defined in claim 8 wherein said wires are welded together at said regions.

10. The improvement defined in claim 9 wherein said regenerator-type heat exchanger is a cold accumulator for use in an air-rectification installation.

References Cited FOREIGN PATENTS 1,294,514 4/1962 France.

ROBERT A. OLEARY, Primary Examiner ALBERT W. DAVIS, Assistant Examiner US. Cl. X.R. 62-13 

